How to Wire & Bridge Subwoofers
Bridging a car audio amplifier will provide the maximum amount of power to a subwoofer system, according to diyaudioandvideo.com. Bridging consists of wiring together two audio channels. Amplifiers must have bridging capability for this practice to work. Bridging two-channel amplifiers will allow for one-channel monaural operation, while bridging four-channel amplifiers yields two-channel (right and left speaker) stereo operation. Because bass frequencies are not as directional as high-range frequencies, bridged subwoofers in one channel mode will not see degradation in sound quality or performance.
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Things You'll Need
- Bridgeable car audio amplifier
- Subwoofer(s)
- Speaker wire
- Terminal connectors
- Wire cutters
Instructions
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1
Check your amplifier's documentation for bridging capability. Note the maximum amount of impedance load the amplifier can handle.
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2
Check the impedance of the individual subwoofers. The documentation that came with the subwoofer will have these impedance values.
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3
Determine the correct impedance load the amplifier will have with the subwoofers connected. Divide the individual speaker impedance value by the number of speakers wired in parallel to arrive at the correct value.
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Purchase or gather the correct gauge speaker wiring for the subwoofers. Depending upon the amplifier and speaker terminal types, you may need to purchase corresponding end connectors to ensure tight and secure connections from the amplifier to the speakers.
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5
Use a pair of wire cutters to cut the speaker wire to the desired length. If necessary, crimp on the end connectors purchased to the speaker wire using the wire cutters.
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Wire the subwoofers in parallel by connecting together the positive terminal of one subwoofer to the other's positive terminal and the negative terminal of one to the other's negative terminal. Connect a single pair of wires to one of the subwoofers. These positive and negative wires will connect directly to the amplifier.
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Read the documentation of the amplifier to determine which speaker wire terminals will correctly bridge the amplifier. Because not all amplifiers share the same design in regards to the terminals used for bridging, one particular amplifier will require use of the left-channel positive terminal and the right-channel negative terminal; other amplifiers require amplifier connections to the right-channel positive and left-channel negative terminals.
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Connect the positive speaker wire leading from the subwoofer(s) to the appropriate right- or left-channel positive terminal of the amplifier. Connect the negative speaker wire leading from the subwoofer(s) to the correct right- or left-channel negative terminal to complete the bridging process.
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Check all the speaker terminal connections for looseness and tighten as necessary. After all the wiring is checked, test the audio system for proper operation, adjust the amplifier crossover and signal boost controls according to manufacturer instructions.
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Tips & Warnings
Purchase speaker wire that conforms to the specification defined by both the amplifier and subwoofer manufacturer.
A capable electronic multi-meter connected to both positive and negative terminals of a subwoofer will display the correct impedance values if documentation is not available.
The subwoofers used in the setup must also have the correct impedance when wiring in parallel. For example, if the amplifier has a maximum bridgeable impedance of 4 ohms, two subwoofers with an individual impedance of 8 ohms, wired in parallel, have a total impedance of 4 ohms when connected to the amplifier.
Certain amplifier and subwoofer terminals such as "easy push" and binding post types alleviate the need for end connectors installed on the speaker wire.
Check the documentation of the amplifier for correct bridge wiring schemes. If an amplifier is incorrectly bridged, damage to the amplifier can occur.
When the amplifier has an impedance load lower than recommended by the manufacturer, damage to the speakers or amplifier will occur.
References
- Photo Credit speaker wire image by Paolo from Fotolia.com
